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kderaad
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Beneficial vs. Non beneficial uses of water
- Beneficial: Crop ET
- -Salt removal
- -Climate control (wind erosion)
- -Cultural practices (cover crops)
- -Weed germination
- Nonbeneficial: everything else
- -excess tailwater
- -excess deep perc.
- -Phreatophyte ET
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Irrigation vs Application Efficiency
- Irrigation: field, farm, district, basin
- -strict accounting of water destinations
- -single event, or annual
- Application Efficiency
- -field
- -makes assumptions - Is the "target" met?
- -Single event only
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Friction
- not a component of energy it destroys energy
- As flow rate decreases in a system, the friction decreases
- Loss of energy as water flows due to water rubbing against walls
- leads to loss of pressure
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Pressure
- Force/Acea (PSi)
- Head- pressure (expressed as height of water)
- The force which is exerted upon an area
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Elevation
Elevation effects pressure, nothing to do with friction
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3 types of energy in water
Elevation, Pressure, Velocity head
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California water use
- Total use:
- -9% urban
- -38% Agriculture
- -38% Environmental
- -15% Miscellaneous
- Developed water supply
- -19% Urban
- -81% Agriculture
- -100% Developed water supply = Ag + Urban
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Federal Projects
- Central valley project
- -lakes and canals
- Coalinga Canal
- Colorado River
- Part of the Aqueduct
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State Water projects
- Oroville dam & reservoir
- Feather river project
- North and south bay aqueducts
- Delta Intake
- CA aqueduct
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Local Water projects
- SF- Bay area
- -Mokelumme lake, Hetch-Hetchy
- Southern CA
- -LA adquate, CO river
- San Diego aqueducts
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Population growth
- will be Southern and Central California
- More demands in urban water use, industrial water use,
- recreation and environment become more important
- More food needed, requires water
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Urban Water supplies
- 20 million + get at least some water form the SWP
- contracts to deliver 4 million acre-feet
- can only deliver 2.4 in wet year and 1.1 in dry year
- more storage needed
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Decline in ag irrigated area
- was 10 million acres now 9
- causes
- -urbanization
- -salinization
- -increasing costs for water
- -availability
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Ground water overdraft
- Subsidence
- dry wells- lower water table
- salt water intrusion
- toxic plumes
- little or no ground water management legislation
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Water marketing/transfers
- surplus water can be sold
- can meet needs without new projects
- Potential damage to in stream users
- promotes excessive ground water pumping
- water transfers are expected to play a significant role in meeting Ca future water needs
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Water conservation
- Does work during drought
- People don't want to conserve during wet years
- decreased revenues for water agencies
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Drainage/selenium/Kesterson reservoir
Drainage: Kesterson, San Luis Drain, Selenium
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Bay-Delta issues
- State and federal pump water out of delta
- supports agriculture
- provides 60% of water in SF
- Various quality issues
- -minimum flows, salinity, temp
- reverse flows
- -more pumps
- widening channels
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Surface irrigation
- 45%
- Furrow
- Border strip
- Level basin
- high flow rate, use CFS doesn't take a lot of energy
- Management Keys: uniform OT, quick advance, short runs, high flow rates, torpedoes, laser leveling
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Pressure
- 20%
- sprinkler
- hand move
- solid set
- center pivot
- linear moves
- side roll
- mid flow rate, 2-3 GPM per sprinkler and 45-60psi
- Management keys: Appl. rate < infilt. rate
- spacing/overlap
- Adequate pressure
- Limit pressure variations
- Check nozzle wear, sizes
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Drip/Micro
- Drip->Incline or online
- Drip tape
- SSDI (sub surface drip irrigation)
- Micro sprayers
- low flow rate, GPH 8-40 psi (low pressure)
- Management Keys:
- Frequent, small applications
- proper timing
- high quality equipment
- prevent clogging
- -water treatment
- -maintenance
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Head
energy (or pressure) in water expressed as a height
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Critical flow devices
- Weirs:
- -Cipolletti weir (supressed or contracted)
- For one flow rate, there is only one corresponding flow depth
- Can have two different depths but same flow rate
- Flumes: water surface elevation charges can measure head loss
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Headloss devices
- submerged orifice
- metergate
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Pipelines
- Propeller meters
- McCrometer magmeters: as fluid passes through the pipe, a voltage directly proportional to the flow rate is generated. Reading converted to rate of flow.
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Types of energy in water
- elevation
- pressure
- velocity head
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